Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Reply-To: Sean Christopherson <seanjc@google.com>
Date:   Fri, 24 Sep 2021 17:55:27 -0700
In-Reply-To: <20210925005528.1145584-1-seanjc@google.com>
Message-Id: <20210925005528.1145584-14-seanjc@google.com>
Mime-Version: 1.0
References: <20210925005528.1145584-1-seanjc@google.com>
Subject: [PATCH 13/14] KVM: x86: Directly block (instead of "halting")
 UNINITIALIZED vCPUs
From:   Sean Christopherson <seanjc@google.com>
To:     Marc Zyngier <maz@kernel.org>, Huacai Chen <chenhuacai@kernel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
        Paul Mackerras <paulus@ozlabs.org>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Janosch Frank <frankja@linux.ibm.com>,
        Paolo Bonzini <pbonzini@redhat.com>
Cc:     James Morse <james.morse@arm.com>,
        Alexandru Elisei <alexandru.elisei@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        David Hildenbrand <david@redhat.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Claudio Imbrenda <imbrenda@linux.ibm.com>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
        linux-mips@vger.kernel.org, kvm@vger.kernel.org,
        kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org,
        David Matlack <dmatlack@google.com>,
        Jing Zhang <jingzhangos@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Go directly to kvm_vcpu_block() when handling the case where userspace
attempts to run an UNINITIALIZED vCPU.  The vCPU isn't halted and its time
spent in limbo arguably should not be factored into halt-polling as the
behavior of the VM at this point is not at all indicative of the behavior
of the VM once it is up and running, i.e. executing HLT in idle tasks.

Note, because this case is encountered only on the first run of an AP vCPU,
vcpu->halt_poll_ns is guaranteed to be '0', and so KVM will not attempt
halt-polling, i.e. this really only affects the post-block bookkeeping.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0d71c73a61bb..b444f9315766 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10127,7 +10127,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 			r = -EINTR;
 			goto out;
 		}
-		kvm_vcpu_halt(vcpu);
+		kvm_vcpu_block(vcpu);
 		if (kvm_apic_accept_events(vcpu) < 0) {
 			r = 0;
 			goto out;
-- 
2.33.0.685.g46640cef36-goog